This invention relates to apparatus for applying foam to a continuously advancing web in general and more particularly to improved apparatus of this nature permitting uniform application through a plurality of spaced nozzles.
Foam applicators for applying foam to an advancing web of material such as a textile web, e.g. a carpet, utilizing a plurality of nozzles are known. Such apparatus is described in U.S. Pat. No. 3,084,661, for example. In this apparatus several foam application nozzles are arranged over the width of the web side by side. The apparatus is used for impregnating a fiber material with a treatment medium contained in a foam, which also may be a dyeing liquid.
Resists which can be applied in foam form, agents which influence the feel or the structure of the web of material, and similar agents may also be considered as the treatment medium for the present invention, in addition to dyeing liquids. The web may be a textile web, but also a nonwoven fabric, a paper web, a plastic web or the like.
It is an object of the present invention to carry out, with apparatus of the basic type described above, a regular pattern application as well as to achieve a uniform application, for instance, plain coloring. In both cases the foam is applied from a multiplicity of nozzles, be it different foams, or foam which is the same everywhere. Frequently, the nozzles will not have separate foam feeding devices, but will be fed from a common foam source.
For liquid pattern making media, such devices which work with nozzles that are supplied in groups, are known, for instance, from British Pat. No. 1,363,724 and U.S. Pat. No. 2,218,811. The known devices comprise one liquid distributor for each individual group, in the form of a tubular canal or a tube section, in which one liquid inlet for feeding the liquid in and several liquid outlets for distributing the liquid to the individual nozzles of the group are provided. Because of the physical pecularity of liquids, the liquid is distributed to the individual nozzles in a sufficiently uniform manner.
This, however, does not apply if foam is to be distributed to different nozzles by means of devices of the kind that are described in British Pat. No. 1,363,724 and U.S. Pat. No. 2,218,811. For, the foam has an entirely different physical behavior, and in particular, a substantially greater mobility than liquid, and pressure cannot be exerted on it to the same degree. It was found that, when distributors of the known type were used, the foam makes a path for itself somewhere and preferably issues from the nozzle located in this path, while the other nozzles are supplied with less foam or none at all. The required uniformity of the foam application from all nozzles can therefore not be achieved in this manner.
It is an object of the present invention to develop apparatus of the type described above, in such a manner that a foam can be distributed uniformly to several application nozzles.